This invention is generally concerned with apparatus for feeding sheets, and, more particularly, with such apparatus including means for facilitating feeding lowermost sheets, one at a time, from an upright stack of sheets disposed on a deck.
U.S. Pat. No. 3,977,668 for DUAL PURPOSE SHEET MATERIAL FEEDING AND SAFETY APPARATUS, issued Aug. 31, 1976 to Bologna, et al. and assigned to the assignee of the present invention, discloses an upright stack of sheets which is supported on a feed deck inclined at an angle relative to an upright wall for urging an edge of each of the sheets into registration with the wall. In addition, there is disclosed opposed output feed rollers situated at the junction between the deck and wall for feeding respective sheets one at a time from the bottom of the stack.
U.S. Pat. No. 4,973,037 for a FRONT END FEEDER FOR MAIL HANDLING MACHINE, issued Nov. 27, 1990 to Holbrook and assigned to the assignee of the present invention, discloses sheet feeding apparatus comparable to the apparatus shown in the aforesaid '688 patent, for use in a high speed machine for handling mixed mail pieces, wherein a drive assembly is provided for feeding successive mailpieces from the bottom of the stack of sheets while maintaining the mailpieces in registration with a fence and fluffing the stack to promote separation of the respective mailpieces from one and other.
When the aforesaid sheet feeding apparatus, and like structures, are utilized for feeding lowermost envelopes or other sheets, one at a time from the bottom of a stack thereof, the stack of sheets may weigh so much that the frictional forces exerted by the stack and deck against the lowermost sheet are such that the lowermost sheet either cannot be fed from the stack or is misfed therefrom. This ordinarily occurs in due to the forces exerted by the feed roller beneath the stack being insufficient to overcome the static frictional forces exerted by the deck and stack on the lowermost sheet or, as the lowermost sheet is exiting the stack, due to the normal force exerted by the stack on the lowermost sheet being insufficient to permit the outfeed rollers to frictionally engage and feed the sheet from beneath the stack. In any event, any given lowermost sheet being fed from the bottom of a stack is subject to different forces in the course of being fed therefrom. Accordingly:
an object of the invention is to provide structure for facilitating feeding successive lowermost sheets from the bottom of a stack thereof, including means for reducing the frictional force exerted on the lowermost sheet in the course of feeding the same; PA0 another object is to provide such facilitating structure for urging successive lowermost sheets toward the outfeed rollers to facilitate feeding thereby; and PA0 another object is to provide such facilitating structure for reducing the weight of the stack on respective lowermost sheets as they are sequentially fed from beneath the stack.